1. Anxiety and depression.
“Studies have shown that not eating enough can cause prolonged periods of anxiety and depression in teens and adults,” says Beal.
If you have a body mass index under 18.5, you may be underweight. Being underweight can increase your risk of malnutrition, developmental problems, infertility, bone fractures and osteoporosis, anemia, increased risk of surgical complications, and a weakened immune system.